Detection of biological species by surface enhanced Raman scattering

This dissertation explores the application of SERS in the detection and characterization of biological species using nanocolloidal silver particles to enhance the Raman signal. Different biological species and biological molecules were evaluated by this technique. Of particular interest is the development of a rapid online detection platform for airborne biological species as well as biological matter in liquid suspensions. These include bacteria and pollen. To interpret the complex spectra of the pathogens, biomolecules such as amino acids, peptides, and proteins, the essential building blocks of a living cell, were studied. To further enhance the Raman signal, novel techniques were explored to ensure better contact between biomolecules and a metallic surface. By electrospraying the charged biomolecular ions from the gas phase onto a solid Ag/AgO surface, we addressed some few fundamental questions regarding the behavior of biomolecules in their surface bound state. Furthermore, the structural sensitivity of Raman spectroscopy provided information about possible structural damage of biomolecules that may have occurred during the landing process.